The objectives of the proposed project are to study: a) the control mechanisms of cell proliferation and organ growth in intact animals using a drug (isoproterenol)-induced hyperplasia and hypertrophy of rodent salivary glands as a model; b) the cell-physiological processes in the submandibular gland that may be connected with cell replication and organ growth; and c) the postnatal development and differentiation of the submandibular gland and the effect of isoproterenol on these processes. The goal for the year covered by the progress report was to analyze further the postnatal differentiation of the submandibular gland, with particular reference to cell replication, and the relationship of isoproterenol-induced hyperplasia and hypertrophy to phenotypic differentiation and normal growth control.